Igniters for use in aircraft turbine engines are typically formed with a metal shell surrounding an insulator. The shell is threaded to engage a threaded igniter opening in the engine. A high voltage terminal is recessed well within a free end of the insulator. A mating high voltage cable connector has a projecting insulator which supports a terminal. The connector insulator extends well into the igniter insulator to establish a long flashover path between the high voltage terminals and the grounded igniter shell. This construction results in a large profile for prior art ignitor and cable connector assemblies. When one common prior art cable connector is secured to an igniter, the cable insulator projects into the igniter insulator and a spring in the cable connector presses the cable terminal against the igniter terminal to establish a high voltage connection. Typically, contact between the terminals takes place only at a point or over a small surface area. An appropriate annular seal is located between the igniter and the cable connector to keep contaminants from entering the space between the igniter and connector insulators. A separate spring may be provided in the connector to compress the seal against the igniter. Any contaminants entering the terminal region may result in igniter and/or cable failure due to flashover. Ideally, the seal will also prevent air from escaping from the space surrounding the terminals when the iqniter is operated at high altitude. As the air pressure across a gap decreases, the flashover voltage required to jump the gap also decreases.
There are many problems with the design of present state of the art igniters and igniter cable connectors. The large number of component parts in aviation engine igniters and igniter cable connectors results in a high manufacturing cost, a large profile and an excessive weight. There is difficulty in establishing and maintaining a good seal between the igniter and the connector and in maintaining a good electrical contact between the igniter and the connector terminals. Operating failures can occur at the seal and also at the contact point between the high voltage connector terminal and the igniter terminal. Any arcing between the terminals caused by poor surface contact will eventually lead to igniter or cable failure.